EFFECTS OF AGING AND EXERCISE ON BONE MASS

随年龄增长的骨量丢失和随之而来的骨折发生率的增加 老年人是一个重大的医疗和社会问题。的确有 目前还没有接受II型或与年龄相关的(老年)治疗 骨质疏松。体育锻炼被认为是一种可能的治疗方法。 对年龄相关性骨丢失采取预防措施，但大多数过去 由于缺乏足够的控制，研究受到了影响。另外， 关于运动之间相互作用的几个重要问题 治疗和其他因素一直没有得到充分的研究。在这 调查，Beagle狗，已被证明随着年龄的增长而失去骨骼 以类似于人类的方式，将被用作研究 增加体育锻炼对对照人群骨量的影响 环境。实验室群体中的24只雌性比格犬，年龄从 8到13年，相当于人类在第六到八十年的时间， 将接受每天20分钟的分级跑步机8次 月份。治疗的效果将在体内使用DUAL进行评估 能量光子吸收测量法或定量数字射线照相术；以及 计算机断层扫描。利用这些技术，人体的骨矿物质含量 股骨远端和中段、腰椎和下颌-上颌骨，以及 股骨中段的皮质几何形状将在12个月前确定。 在治疗开始和结束时，以及治疗后8个月 治疗。治疗前的个体基线变化率 参数将与治疗期间和治疗后的变化率进行比较。 治疗周期。动物在所有时期的活动水平也将 被监视。这项研究的长期目标是确定 中等强度的体育锻炼可以用来治疗或预防衰老- 相关的骨质流失。几个具体因素的影响 运动治疗的疗效将被调查：初始受试者年龄 以及机械负荷中的相对活动水平或基线增加， 以及在运动治疗期后对解除条件的反应。

Loss of bone mass with aging and consequent increase in fracture incidence among the elderly is a major medical and societal problem. There is currently no accepted treatment for type II, or age-related (senile) osteoporosis. Physical exercise has been suggested as a possible treatment for or preventive measure against age-related bone loss, but most past studies have been compromised by lack of sufficient controls. Also, several important issues regarding the interaction between exercise treatment and other factors have been inadequately studied. In this investigation, the Beagle dog, which has been shown to lose bone with aging in a manner similar to that of humans, will be used as a model to study the effects of increased physical exercise on bone mass in a controlled environment. 24 female Beagles in a laboratory colony ranging in age from 8 to 13 years, equivalent to humans in the sixth through eighth decades, will be subjected to 20 minutes per day of graded treadmill running for 8 months. The effects of the treatment will be evaluated in vivo using dual energy photon absorptiometry or quantitative digital radiography, and computed tomography. Using these techniques, bone mineral content of the distal and midshaft femur, lumbar vertebrae, and mandible-maxillae, and cortical geometry of the midshaft femur will be determined 12 months prior to treatment, at the beginning and end of treatment, and 8 months after treatment. Individual pre-treatment baseline rates of change in these parameters will be compared with rates of change during treatment and post- treatment periods. Activity levels of the animals in all periods will also be monitored. The long-term goal of the study is to determine if moderately strenuous physical exercise can be used to treat or prevent age- related bone loss. The influence of several specific factors on the efficacy of exercise treatment will be investigated: initial subject age and relative activity level or baseline increases in mechanical loading, and response to deconditioning following an exercise treatment period.